This program project is based on the hypothesis that vascular cell redox status plays a critical role in atherosclerosis. Oxidative stress (an imbalance between oxidants and anti-oxidants in favor of the former) has been implicated as an etiologic factor in atherogenesis and vascular dysfunction through the oxidation of low-density lipoprotein (LDL), stimulation of monocyte-endothelial interactions, and impaired biologic action of endothelium-derived nitric oxide (EDNO). While previous studies have evaluate the effects of LDL-associated and extracelluar antioxidants, little is known about the role of intracellular antioxidants. Therefore the intracellular concentrations and redox status of vitamin C and glutathione (GSH), in LDL oxidation and EDNO production, as well as in preventing cellular dysfunction in the face of an oxidative stress. Project 1 will investigate vitamin C and GSH metabolism in human vascular cells, and explore the mechanisms by which these intracellular antioxidants affect cell-mediated LDL oxidation and the expression of cellular adhesion molecules. Project 2 will examine the importance of cellular redox status for the function of mitochondria in vascular cells. Age associated changes in mitochondrial function and cellular redox status will be examined and related to vascular function and atherosclerosis. Project 3 will define the role of intracellular antioxidant status in the synthesis and release of EDNO by human aortic endothelial cells under normal and oxidative stress conditions. Findings from cell culture experiments in projects 1-3 will be expanded to the in vivo level, using experimental animals fed an atherogenic diet and vitamin C and/or GSH modulating agents. Project 4 will perform clinical studies in patients with coronary artery disease (CAD) that parallel the basic studies in Projects 1-3. Vitamin C and GSH status will be manipulated and the resulting effects on endothelium-dependent vasodilation and other endothelial functions will be explored. The information gained from this interactive and multi-disciplinary program project will provide a better understanding of the mechanisms by which antioxidants modify atherogenesis and suggest new strategies for the prevention of CAD.